The present invention relates to a multifunctional card having a static protection means.
2. Description of the Related Art
In a conventional multifunctional card, such as a memory cassette, semiconductor circuits mounted into the cassette are damaged by electrostatic. For protecting the card from the adverse effects of static, a metal cover or housing of a multifunctional card is generally grounded. However, a housing made of a plastic material is often used in a consideration of a cost or a request from a customer. In a multifunctional card using a plastic housing, the static generated from a human body is discharged onto a substrate through a mating portion of the housing, so that destruction of elements, such as ICs, may occur.
According to conventional techniques, when a housing is to be made of a plastic material, in order to prevent the static caused destruction, a structure allowing a great creeping distance is generally employed, or complete insulation is performed (by an adhesive agent, sealing, ultrasonic welding, or the like). In the former technique, a complicated structure is required to perform completely static protection and hence problems are posed in terms of reliability, cost, and the like. In the latter technique, manufacturing processes become complicated, and a problem is posed when the housing is posed afterward.